An I/O control system in a virtual machine system has at least one virtual machine (VM) running under control of a virtual machine control program (VMCP) and has a direct I/O execution mode in which an I/O interruption to the I/O device dedicated by the running VM is directly executed without intervention...http://www.google.ca/patents/US4887202?utm_source=gb-gplus-sharePatent US4887202 - Input-output control method in a virtual machine system
